VP9 codec controls for screensharing

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

Index: webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
index 73beab37b0627c44f065a784afd7e8f601281894..31484b68799cdf63d33faf290af874122eed6e32 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
@@ -404,6 +404,13 @@ int VP9EncoderImpl::InitAndSetControlSettings(const VideoCodec* inst) {
   vpx_codec_control(encoder_, VP9E_SET_NOISE_SENSITIVITY,
                     inst->codecSpecific.VP9.denoisingOn ? 1 : 0);
 #endif
+  if (codec_.mode == kScreensharing) {
+    // Adjust internal parameters to screen content.
+    vpx_codec_control(encoder_, VP9E_SET_TUNE_CONTENT, 1);
+    // Let the encoder skip the encoding of very flat/low content blocks.

[stefan-webrtc, 2015/09/04 09:31:51]

As you say, we probably want to do this for regular content too. I think we
should evaluate if that helps.

AFAIK we are doing this for all content modes in VP8.

[ivica, 2015/09/04 09:40:41]

marpan@ told me to add this, and only for screensharing for now. We can easily
changed that later.

+    vpx_codec_control(encoder_, VP8E_SET_STATIC_THRESHOLD, 1);
+  }
+
   inited_ = true;
   return WEBRTC_VIDEO_CODEC_OK;
 }